Primary Iron Overload With Inappropriate Hepcidin Expression in V162del Ferroportin Disease
Heinz Zoller,1,2 Ian McFarlane,3 Igor Theurl,4 Sylvia Stadlmann,5 Elizabeta Nemeth,6 David Oxley,7 Tomas Ganz,6 David J. Halsall,3 Timothy M. Cox,2 and Wolfgang Vogel1
Ferroportin disease (hemochromatosis type 4) is a recently recognized disorder of human iron metabolism, characterized by iron deposition in macrophages, including Kupffer cells. Mutations in the gene encoding ferroportin 1, a cellular iron exporter, are responsible for this iron storage disease, inherited as an autosomal dominant trait. We present clinical, histopathological, and radiological ﬁndings in a family with the most common ferroportin mutation, V162del. In the index case, the disorder is characterized by abundant deposition of hemosiderin in all tissues investigated (mesenteric lymph node, liver, gastric and duodenal mucosa, and also in squamous cell carcinoma of the lung). The radiological ﬁndings indicated the presence of excess iron in bone marrow and spleen. Despite a signiﬁcant burden of iron, no features of chronic liver disease were found in affected members of the family, including individuals aged up to 80 years. Hyperferritinemia greater than 1,000 fg/L was a penetrant biochemical ﬁnding before the second decade in life and was associated with signiﬁcantly increased serum concentrations of pro-hepcidin that correlated positively with urinary hepcidin concentrations. In conclusion, the systemic iron burden in ferroportin disease is not a sufﬁcient cause for chronic liver disease. In patients with most, but not all, ferroportin mutations, retention of iron in macrophages of the liver and other organs may protect against damage to parenchymal cells. Finally, macrophage iron storage in ferroportin disease is associated with elevated serum pro-hepcidin levels. (HEPATOLOGY 2005;42:466-472.)
utations in the human gene encoding ferroportin 1 (FPN1/IREG-1/MTP-1/SLC40A1) are associated with an unusual iron overload syndrome, recently named hemochromatosis type 4 or ferroportin disease.1-9 Clinically, ferroportin disease is rarely associated with hepatic cirrhosis, and the principal pathological ﬁnding is iron deposition predominantly in
Abbreviations: MRI, magnetic resonance imaging; CT, computed tomography; PCR, polymerase chain reaction.
From the Clinical Divisions of 1Gastroenterology and Hepatology, and 4General Internal Medicine, Innsbruck Medical University, Innsbruck, Austria; 2Department of Medicine, University of Cambridge, Cambridge, UK; 3Department of Clinical Biochemistry, Cambridge University Hospitals NHS Trust, Cambridge, UK;5Department of Pathology, Innsbruck Medical University, Innsbruck, Austria; 6Department of Medicine, David Geffen School of Medicine, University of California, Los Angeles, CA; and 7Babraham Institute, Cambridge, UK.
Received November 1, 2004; accepted May 11, 2005.
Supported by the Wellcome Trust, the Sackler Foundation, the Verein zur Fo¨rderung der Forschung in Gastrenterologie und Hepatologie, and the BBSRC.
Address reprint requests to: Heinz Zoller, Department of Medicine, University of Cambridge, Addenbrooke’s Hospital, Level 5, Box 157, Hills Road, Cambridge CB2 2QQ, United Kingdom. E-mail: [email protected]; fax: (44) 1223-336846.
Copyright © 2005 by the American Association for the Study of Liver Diseases.
Published online in Wiley InterScience (www.interscience.wiley.com).
Potential conﬂict of interest: Nothing to report.
cells of monocytic macrophage lineage—mainly and conspicuously Kupffer cells within the liver.
The most common FPN1 mutation is deletion of a valine at position 162 and has been identiﬁed in patients of various ethnic backgrounds.3,8,10,11 Deletion of this amino acid causes loss of function and when studied in vitro causes accumulation of iron in cultured cells.12 FPN1 is a putative transmembrane iron channel implicated in the egress of iron from duodenal enterocytes, macrophages, hepatocytes, and placenta (reviewed in McKie and Barlow13). Impaired iron export from macro-phages in patients with mutations in the FPN1 gene has been proposed as the explanation for the accumulation of iron that occurs in organs containing abundant macro-phages such as the liver, spleen, and bone marrow.14
The differential diagnosis of iron accumulation in macrophages also includes the anemia of inﬂammation, in which anemia is associated with inappropriate retention of iron in macrophages and hepatocytes despite iron-restricted erythropoiesis.15
Hepcidin, which is expressed in the liver, heart,16 and kidney,17 is the key mediator of anemia of inﬂammation,18,19 and synthetic hepcidin was shown to interact physically with ferroportin in a cellular overexpression system, causing internalization and degradation, and decreased export of iron.20 Because hepcidin expression increases in response to iron loading (reviewed in Ganz21), a feedback loop in which body iron homeostasis is controlled by hepcidin has been postulated.
The important physiological function of hepcidin is further demonstrated by the observation that homozygous mutations in hepcidin have been identiﬁed in 4 pedigrees with juvenile hemochromatosis.22-25 Moreover, targeted disruption of the hepcidin gene in mice induces severe iron overload of the liver and pancreas, resembling that observed in human hemochromatosis.26 In the classical HFE1-associated hemochromatosis (hemochromatosis type 1), as well as in rare hemochromatosis due to homozygous mutations in genes encoding transferrin receptor 2 (hemochromatosis type 3) or hemojuvelin (hemochromatosis type 2), liver hepcidin mRNA expression or urinary hepcidin excretion appears to be inappropriately low, a ﬁnding that may explain the persistently increased absorption of iron in the face of systemic iron excess in these diseases.27-29 We present the clinical, radiological, histological, and biochemical ﬁndings in a pedigree affected by ferroportin disease (hemochromatosis type 4). Extrahepatic iron deposition in an adult man led to the diagnosis and, as a result, investigations identiﬁed 4 more affected individuals. In all affected individuals, serum pro-hepcidin concentrations before iron depletion therapy were found to be increased more than threefold above the mean concentration in healthy persons, and a statistically signiﬁcant correlation between serum pro-hepcidin concentrations and urinary hepcidin excretion was found.
Patients and Methods
Informed consent was obtained from all patients involved in the study. DNA for genetic testing was prepared from venous blood samples using the QiaAMP DNA mini Kit (Qiagen, Hilden, Germany) according to the manufacturer’s instructions. Genetic testing for C282Y mutation in the HFE gene was performed as previously described.30 Molecular analysis of the human ferroportin gene (FPN1, HFE4) was carried out as follows: each exon, including intron–exon boundaries, was polymerase chain reaction (PCR) ampliﬁed, and direct sequencing analysis carried out on an ABI Prism 310 automated sequencer. Primers and PCR conditions were used as described in Cazzola et al.8 Serum iron parameters were determined using standard laboratory techniques (Abbott, Vienna, Austria).
Pro-hepcidin ELISA was purchased from DRG Diagnostics (Marburg, Germany) and carried out following the maufacturer’s instructions and as previously de-
Fig. 1. (A) Mesenteric lymph node with brown hemosiderin deposits on HE staining (arrows) (original magniﬁcation X200). (B) Duodenal biopsy–stainable iron in villous macrophages (Perls’ Prussian blue stain; original magniﬁcation X100). (C) Gastric antrum biopsy–stainable iron in gastric mucosa (original magniﬁcation X200). (D) Squamous cell carcinoma of the lung–stainable iron in tissue macrophages (Perls’ Prussian blue stain; original magniﬁcation X100).
scribed.31 For quantiﬁcation of serum pro-hepcidin, frozen serum samples were used, avoiding repeated freeze– thaw cycles, which can cause signiﬁcant pro-hepcidin degradation. Tissues were embedded in parafﬁn and stained with hematoxylin-eosin according to standard techniques. Perls’ Prussian blue stain was carried out as described by Perls32 and Stevens.33
Measurement of urinary hepcidin concentration was carried out as described elsewhere.34
Index Case. Patient no. 1 underwent cholecystectomy for symptomatic cholelithiasis in 1986, when histological examination of a macroscopically suspicious mesenteric lymph node indicated marked iron deposition (Fig. 1). The 68-year-old patient was subsequently found to have a serum ferritin of 5,265 Ig/L (reference range, 5-307 Ig/L) and a serum transferrin saturation of 37.5% (reference range, 20%-50%). Initial genetic investigations for hereditary hemochromatosis type 1 showed the HLA phenotype A2/A3, B7/B40, BW 6/CW 3, of which A3 and B7 are known to be associated with this hemochromatosis type 1 (HFE1). However, HFE1 genotyping, which was performed in 1997, showed no pathological mutations in the HFE1 gene. The patient refused liver biopsy, but magnetic resonance imaging showed abnormal signals in the liver, spleen, and bone marrow, indicating tissue iron storage.
In light of these ﬁndings, secondary causes for iron overload, such as heavy alcohol consumption or ironloading anemias, were excluded. Neither was there any evidence of chronic inﬂammation, which could cause sequestration of iron in macrophages. Therapeutic phlebotomy was started after serum iron parameters remained unchanged over 5 years. Phlebotomy was well tolerated, and a total of 22 L of blood were removed over a period of 22 months (equivalent to approximately 12 g iron). During this treatment, serum ferritin decreased from 5,265 Ig/L to 1,140 Ig/L. Although hemoglobin levels were never below 12 g/dL, therapeutic phlebotomy was stopped for 8 months because of non-compliance, which resulted in an increase in serum ferritin concentration to 2,111 Ig/L. On follow-up hemoglobin, aminotransferases, bilirubin, and coagulation tests remained normal; furthermore, sonography and esophagoscopy showed neither signs of chronic liver disease nor portal hypertension, respectively.
At the age of 77 years, the patient complained of gradually worsening shortness of breath: a diagnosis of squa-
HEPATOLOGY, August 2005
mous carcinoma of the bronchus was made by biopsy of a tumor obstructing a main bronchus. At the age of 80 years, the patient died of complications of the carcinoma after a course of palliative radiation therapy.
On family screening for iron overload, 2 sons of the index case were found to have iron overload (Fig. 2), one aged 29 (patient no. 5) with a serum ferritin of 4,935 Ig/L and one at the age of 50 (patient no. 4) with a serum ferritin of 7,239 Ig/L. The latter ﬁnding may have been exacerbated by heavy consumption of alcohol before presentation. Of the 2 remaining sons, 1 had a normal serum ferritin and the other was not available for a medical investigation. In the third generation of this family, the 17-year-old twin sons of patient no. 3 were found to have serum ferritin concentrations of 1,150 Ig/L and 1,324 Ig/L. The serum iron parameters of all family members available for investigation are displayed in Table 1.
In all affected family members, phlebotomy was well tolerated, and in patient no. 5 fortnightly therapeutic phlebotomy for 23 months resulted in a decline of serum ferritin concentrations from 4,935 Ig/L to 345 Ig/L. Complete hematological and biochemical parameters remained within the normal range during follow-up. In all other cases, the diagnosis was established only recently, and hence data on the effects of prolonged phlebotomy are not yet available.
Histopathology. Histological examination of the macroscopically suspicious mesenteric lymph node, which was removed during the cholecystectomy, showed hemosiderin deposits (Fig. 1A).
The patient refused liver biopsy, which was offered after identiﬁcation of stainable iron in the lymph node that led to the detection of hyperferritinemia. However, during follow-up, gastroduodenoscopy was performed at the age of 65 years for upper abdominal pain. Histological examination of the duodenal biopsy showed stainable iron in the villous macrophages. Furthermore, histological examination of the squamous cell bronchial carcinoma
Table 1. Serum Iron Parameters of All Family Members Available for Detailed Investigation
NOTE. Affected individuals are listed in italics.
Fig. 3. Images of a T2-weighted MRI scan of the abdomen of patient no. 5. Note the low signal intensity in liver, spleen, and bone marrow with normal signal intensities in pancreas and kidneys. (A) Abdomen transversal section showing iron accumulation in the liver and spleen. (B) Abdomen transversal section showing no iron accumulation in pancreas and kidneys.
(epidermoid cellular) also reﬂected increased stainable iron in tumor-associated macrophages (Fig. 1D).
The liver biopsy of patient no. 2 at the age of 29 years is shown in Fig. 2, where excessive brown deposits (hemosiderin) within the liver were found. Unlike patients with classical HFE1-associated hemochromatosis, no hemosiderin and little stainable iron were detected in hepatocytes; hemosiderin was mainly found in the sinusoids. Perls’ Prussian blue stain of the liver conﬁrmed severe iron accumulation, predominantly in Kupffer cells (Fig. 2B,D). No signs of inﬂammatory liver disease or ﬁbrosis were found. Taken together, these ﬁndings demonstrate that ferroportin disease (hemochromatosis type 4) caused by the V162del mutation is a systemic disorder in which the macrophage is the principal cell affected.
Radiology. To exclude hepatocellular carcinoma at the time of presentation with severe iron overload and to further assess the severity of hepatic iron overload, magnetic resonance imaging (MRI) was performed. The signal intensity of T2-weighted MRI scans of the liver was signiﬁcantly reduced in patient 1 and patient 5, which accords with the histological ﬁndings that demonstrated heavy iron deposits in the liver. Furthermore, T2 signal intensities in spleen and bone marrow were also reduced in both patients, suggestive of iron deposition in these macrophage-rich organs (Fig. 3). Computed tomography scanning of the abdomen was carried out during surveillance for hepatocellular carcinoma every 3 years, on which radiological changes, compatible with iron deposition in liver, spleen, and lymph nodes, were found (not shown). Signal hyperintensity of the liver with negative contrast of the liver veins and signal hyperintensity of the spleen are known to be nonspeciﬁc CT ﬁndings, which can be due to iron deposition.
Genetics. The pedigree is displayed in Fig. 4A. The inheritance pattern is characteristic of an autosomal dominant trait, with affected individuals represented in all 3 generations. Sequencing of the ferroportin gene revealed the most common ferroportin mutation (a deletion of 3 base pairs in exon 5), which results in loss of a valine in position 162 (V162del) of the predicted ferroportin1 protein. The gene mutation is fully penetrant at the biochemical level, with hyperferritinemia present in all heterozygous family members. Unaffected family members in all 3 generations were found to have normal serum ferritin concentrations. Mutations in all other exons of the ferroportin gene were excluded by complete sequencing of the coding region. In summary, the mutation was fully penetrant and co-segregated with the phenotype of hyperferritinemia and normal serum transferrin saturation in this family.
Serum Pro-hepcidin. In the 3 affected individuals from whom pre-treatment serum samples were available serum pro-hepcidin concentrations were 288 ng/mL, 429 ng/mL, and, 649 ng/mL, all of which are above the reported range in healthy individuals (52-153 ng/mL).31 Furthermore, these values are even higher than the reported median for chronic renal insufﬁciency (148 ng/ mL).31 In the 2 affected family members (patient 1 and patient 2) from whom serum samples were available only after initiation of treatment, serum pro-hepcidin concentrations were determined at 68 ng/mL and 159 ng/mL, respectively. During venesection therapy, the concentration of serum pro-hepcidin gradually decreased.
As shown in Fig. 5B, a statisticaly signiﬁcant correlation between serum pro-hepcidin concentration and urinary hepcidin concentration was found (Deming regression analysis correlation coefﬁcient 0.98, P < .001).
Hyperferritinemia is a common ﬁnding in clinical practice, and the differential diagnoses include many clinical conditions such as chronic liver disease, iron-loading anemias, inﬂammation, and malignant diseases, in all of which serum iron and transferrin saturation are usually decreased. HFE1-associated hemochromatosis is a frequent cause of hyperferritinemia but usually is associated with elevated serum iron concentrations and transferrin saturation. Recent advances in the study of hereditary iron overload syndromes have shown that hereditary hemochromatosis can be caused by homozygous mutations in several other genes (TfR2, HJV, HAMP)35 and may be associated with more complex compound genotypes.35,36
In this pedigree, the abnormalities were associated with the most common ferroportin mutation, V162del. On
Fig. 4. (A) Pedigree of a family with iron storage associated with a mutation in the human ferroportin gene. Affected individuals, heterozygous for the V162del mutation, are represented by solid symbols, which are labeled with age at diagnosis (above) and serum ferritin values (below). (B) DNA Sequence electropherograms of an unaffected (above) and an affected individual (below). Note that GTT (484-486) is missing, resulting in an in-frame deletion on one allele and loss of a valine residue at position 162 of the mature protein.
histological examination of various tissues, iron deposition was found not only in Kupffer cells but also in many other types of macrophages. Stainable iron was detected in duodenal villous macrophages, lymph node macro-phages, and the tumor macrophages associated with squamous cell carcinoma of the lung. Systemic macrophage iron overload was further supported by the ﬁndings of the CT and MRI scans, where the radiological abnormalities were strongly indicative of increased tissue iron in spleen and bone marrow.
The total burden of iron in the body was apparently very high in at least 2 affected members of this pedigree, as suggested by high serum ferritin concentrations and by estimation of mobilizable iron during therapeutic phlebotomy. The high iron burden is notable, because no clinical, histological, biochemical, or radiological signs of liver disease or extrahepatic manifestations of hemochromatosis could be found; cardiomyopathy, diabetes mellitus, arthropathy, hypogonadism, or endocrinopathy (reported clinical features in patients with the N144H mutation in the ferroportin gene9), were signiﬁcant by their absence. Furthermore, unlike other reported cases of ferroportin disease (hemochromatosis type 4)9,10 in patients with the V162del mutation, therapeutic phlebotomy was well tolerated and iron could be readily mobilized without induction of anemia.
The absence of any clinical manifestation of iron-storage disease in this pedigree even in individuals of advanced age, however, raises the question as to whether phlebotomy should have been started at all. Liver ﬁbrosis and cirrhosis are rare in hemochromatosis type 4 and have been mostly associated with a different class of ferroportin mutations, which result in a phenotype similar to classical hemochromatosis, with iron deposition in hepatocytes and increased transferrin saturation.3-10,37,38 The severity of iron deposition in Kupffer cells and the absence of stainable iron in hepatocytes in the liver biopsy for patient no. 5 suggests that iron loading of macrophages is well tolerated, but equivalent loading of hepatocytes may be the cause of ﬁbrosis and cirrhosis in classical hemochromatosis.39
Relative hepcidin deﬁciency has been reported in HFE1-associated hemochromatosis, juvenile hemochromatosis, and TfR2-associated hemochromatosis.29,31,34 Here we provide a report of serum pro-hepcidin expression in ferroportin syndrome (hemochromatosis type 4) in which we demonstrate a strong correlation between serum pro-hepcidin concentration and urinary hepcidin concentrations in individuals with elevated hepcidin expression. In contrast to other types of hemochromatosis, serum pro-hepcidin concentrations in patients heterozygous for the V162del mutations in the ferroportin gene were found to be markedly increased, which is in accordance with a recent study demonstrating increased urinary hepcidin concentrations34 in other patients with this mutation. The increase, however, appears to be dynamic so that hepcidin remains responsive to changes in iron status, because phlebotomy resulted in a gradual decrease in serum pro-hepcidin in at least 2 patients. The processing of pro-hepcidin to hepcidin, however, has not yet been characterized, and it is uncertain as to whether serum pro-hepcidin and urinary hepcidin also correlate in other disorders of iron homeostasis.
One explanation for the coexistence of systemic iron overload with high hepcidin concentrations, which should reduce iron absorption, is that the hepcidin signal can be overridden by another signal that induces iron absorption. In our youngest patients, aged 17 years, serum ferritin concentrations were greater than 1,000 Ig/L, and serum pro-hepcidin concentrations also were increased. Because we observed an age-dependent increase in serum ferritin and pro-hepcidin, iron absorption in these patients was still inappropriately high, even though serum (pro-)hepcidin concentrations were elevated. In the light of this observation, we question whether there is indeed an unidentiﬁed “erythroid regulator” inducing iron absorption, as proposed by the late Clement Finch.40 If so , such an entity appears to override the effect of high (pro)-hepcidin concentrations.40 However, the severe iron overload phenotype in patients with hepcidin deﬁciency22,23 and the severe iron deﬁciency that develops in mice41 or humans42 overexpressing hepcidin strongly suggests that this peptide is the principal determinant of iron absorption in mammals.
Recently, Nemeth et al.20 found that synthetic hepcidins bind to ferroportin expressed as a fusion protein in cultured cells, thereby inducing ferroportin internalization and its subsequent degradation.20 As shown in vitro, if the V162del ferroportin variant is overexpressed in cell lines, no such internalization can be induced by synthetic hepcidin.43 However, because hemochromatosis type 4 has only been recognized in individuals heterozygous for mutations in the human ferroportin gene, the contribution of ferroportin expressed from the coexistent wild-type allele to the disease phenotype cannot readily be unraveled.
There are indications that type 4 hemochromatosis itself is a heterogeneous disorder whose phenotype depends on the nature of the mutation affecting the ferroportin molecule. Thus, at least some patients with mutations in amino acid 144 have been reported to show increased transferrin saturation and evidence of liver disease, without any other known causes for systemic iron overload or hepatocyte iron loading. Ferroportin is highly expressed in duodenal enterocytes, hepatocytes, and macrophages (as well as in the placenta). It is conceivable that certain mutations do not induce a major bottleneck to iron release from macrophages but still display resistance to the inhibitory effects of hepcidin on iron export. In such patients, the phenotype could be dominated by excessive intestinal iron absorption unresponsive to increased hepcidin concentrations. Other patients, including those harboring V162del mutations, may be primarily affected by the consequences of functional deﬁciency of ferroportin in macrophages. Paradoxically, retention of iron in macrophages may protect these patients against injury to parenchymal cells in the liver and other organs, even when intestinal absorption and systemic iron load are also increased.
In summary, we report here detailed studies in a pedigree with an unusual presentation of hemochromatosis type 4 that highlight the systemic nature of the disorder. Despite a greatly increased burden of iron, chronic liver disease is not the clinical hallmark of the disorder. Finally, we report high serum pro-hepcidin concentrations that were apparent in the early stages of hemochromatosis type 4 —an unexpected ﬁnding, because aquisition of iron by absorption at this stage of the disorder is increased.
Acknowledgment: The authors thank all patients and family members for participation in the study. We also thank Dr. M. Schocke for provision of MR images, Dr. Peter Obrist and Prof. Gregor Mikuz for initial review of the histology, and Dr. Franz-Josef Willhelm as well as Dr. Christian Hallbrucker for collection of clinical data. The excellent technical assistance of Ms. Barbara Wimmer and Ms. Gisela Egg is acknowledged.
- Njajou OT, Vaessen N, Joosse M, Berghuis B, van Dongen JW, Breuning MH, et al. A mutation in SLC11A3 is associated with autosomal dominant hemochromatosis. Nat Genet 2001;28:213-214.
- Montosi G, Donovan A, Totaro A, Garuti C, Pignatti E, Cassanelli S, et al. Autosomal-dominant hemochromatosis is associated with a mutation in the ferroportin (SLC11A3) gene. J Clin Invest 2001;108:619-623.
- Roetto A, Merryweather-Clarke AT, Daraio F, Livesey K, Pointon JJ, Barbabietola G, et al. A valine deletion of ferroportin 1: a common mutation in hemochromatosis type 4. Blood 2002;100:733-734.
- Wallace DF, Pedersen P, Dixon JL, Stephenson P, Searle JW, Powell LW, et al. Novel mutation in ferroportin1 is associated with autosomal dominant hemochromatosis. Blood 2002;100:692-694.
- Arden KE, Wallace DF, Dixon JL, Summerville L, Searle JW, Anderson GJ, et al. A novel mutation in ferroportin1 is associated with haemochromatosis in a Solomon Islands patient. Gut 2003;52:1215-1217.
- Jouanolle AM, Douabin-Gicquel V, Halimi C, Loreal O, Fergelot P, Delacour T, et al. Novel mutation in ferroportin 1 gene is associated with autosomal dominant iron overload. J Hepatol 2003;39:286-289.
- Hetet G, Devaux I, Souﬁr N, Grandchamp B, Beaumont C. Molecular analyses of patients with hyperferritinemia and normal serum iron values reveal both L ferritin IRE and 3 new ferroportin (slc11A3) mutations. Blood 2003;102:1904-1910.
- Cazzola M, Cremonesi L, Papaioannou M, Soriani N, Kioumi A, Charalambidou A, et al. Genetic hyperferritinaemia and reticuloendothelial iron overload associated with a three base pair deletion in the coding region of the ferroportin gene (SLC11A3). Br J Haematol 2002;119:539-546.
- Pietrangelo A, Montosi G, Totaro A, Garuti C, Conte D, Cassanelli S, et al. Hereditary hemochromatosis in adults without pathogenic mutations in the hemochromatosis gene. N Engl J Med 1999;341:725-732.
- Devalia V, Carter K, Walker AP, Perkins SJ, Worwood M, May A, et al. Autosomal dominant reticuloendothelial iron overload associated with a 3-base pair deletion in the ferroportin 1 gene (SLC11A3). Blood 2002; 100:695-697.
- Gordeuk VR, Calefﬁ A, Corradini E, Ferrara F, Jones RA, Castro O, et al. Iron overload in Africans and African-Americans and a common mutation in the SCL40A1 (ferroportin 1) gene. Blood Cells Mol Dis 2003;31:299-304.
- Schimanski LM, Drakesmith H, Merryweather-Clarke AT, Viprakasit V, Edwards JP, Sweetland E, et al. In vitro functional analysis of human ferroportin (FPN) and hemochromatosis-associated FPN mutations. Blood 2005;105:4096-4102.
- McKie AT, Barlow DJ. The SLC40 basolateral iron transporter family (IREG1/ferroportin/MTP1). Pﬂugers Arch 2004;447:801-806.
- Fleming RE, Sly WS. Ferroportin mutation in autosomal dominant hemochromatosis: loss of function, gain in understanding. J Clin Invest 2001; 108:521-522.
- Weiss G. Pathogenesis and treatment of anaemia of chronic disease. Blood Rev 2002;16:87-96.
- Pigeon C, Ilyin G, Courselaud B, Leroyer P, Turlin B, Brissot P, et al. A new mouse liver-speciﬁc gene, encoding a protein homologous to human antimicrobial peptide hepcidin, is overexpressed during iron overload. J Biol Chem 2001;276:7811-7819.
- Kulaksiz H, Theilig F, Bachmann S, Gehrke SG, Rost D, Janetzko A, et al. The iron-regulatory peptide hormone hepcidin: expression and cellular localization in the mammalian kidney. J Endocrinol 2005;184:361-370.
- Rivera S, Liu L, Nemeth E, Gabayan V, Sorensen OE, Ganz T. Hepcidin excess induces the sequestration of iron and exacerbates tumor-associated anemia. Blood 2004;105:1797-1802.
- Nemeth E, Valore EV, Territo M, Schiller G, Lichtenstein A, Ganz T. Hepcidin, a putative mediator of anemia of inﬂammation, is a type II acute-phase protein. Blood 2003;101:2461-2463.
- Nemeth E, Tuttle MS, Powelson J, Vaughn MB, Donovan A, Ward DM, et al. Hepcidin regulates iron efﬂux by binding to ferroportin and inducing its internalization. Science 2004;306:2090-2093.
- Ganz T. Hepcidin in iron metabolism. Curr Opin Hematol 2004;11:251
HEPATOLOGY, August 2005
- Roetto A, Daraio F, Porporato P, Caruso R, Cox TM, Cazzola M, et al. Screening hepcidin for mutations in juvenile hemochromatosis: identiﬁcation of a new mutation (C70R). Blood 2004;103:2407-2409.
- Roetto A, Papanikolaou G, Politou M, Alberti F, Girelli D, Christakis J, et al. Mutant antimicrobial peptide hepcidin is associated with severe juvenile hemochromatosis. Nat Genet 2003;33:21-22.
- Matthes T, Aguilar-Martinez P, Pizzi-Bosman L, Darbellay R, Rubbia-Brandt L, Giostra E, et al. Severe hemochromatosis in a Portuguese family associated with a new mutation in the 5’-UTR of the HAMP gene. Blood 2004;104:2181-2183.
- Delatycki MB, Allen KJ, Gow P, MacFarlane J, Radomski C, Thompson J, et al. A homozygous HAMP mutation in a multiply consanguineous family with pseudo-dominant juvenile hemochromatosis. Clin Genet 2004;65:378-383.
- Nicolas G, Bennoun M, Devaux I, Beaumont C, Grandchamp B, Kahn A, et al. Lack of hepcidin gene expression and severe tissue iron overload in upstream stimulatory factor 2 (USF2) knockout mice. Proc Natl Acad Sci U S A 2001;98:8780-8785.
- Bridle KR, Frazer DM, Wilkins SJ, Dixon JL, Purdie DM, Crawford DH, et al. Disrupted hepcidin regulation in HFE-associated haemochromatosis and the liver as a regulator of body iron homoeostasis. Lancet 2003;361: 669-673.
- Papanikolaou G, Samuels ME, Ludwig EH, MacDonald ML, Franchini PL, Dube MP, et al. Mutations in HFE2 cause iron overload in chromosome 1q-linked juvenile hemochromatosis. Nat Genet 2004;36:77-82.
- Nemeth E, Roetto A, Garozzo G, Ganz T, Camaschella C. Hepcidin is decreased in TFR2 hemochromatosis. Blood 2005;105:1803-1806.
- de Kok JB, Wiegerinck ET, Giesendorf BA, Swinkels DW. Rapid genotyping of single nucleotide polymorphisms using novel minor groove binding DNA oligonucleotides (MGB probes). Hum Mutat 2002;19:554-559.
- Kulaksiz H, Gehrke SG, Janetzko A, Rost D, Bruckner T, Kallinowski B, et al. Pro-hepcidin: expression and cell speciﬁc localisation in the liver and its regulation in hereditary haemochromatosis, chronic renal insufﬁciency, and renal anaemia. Gut 2004;53:735-743.
- Perls M. Nachweis von Eisenoxyd in gewissen Pigmentationen. Virchows Archive fu¨r pathologische Anatomie und fu¨r Klinische Medizin 1867;39:42.
- Stevens A. Pigments and minerals. In: Bancroft JD, Stevens A, eds. Theory and Practice of Histological Techniques. 2nd ed. Edinburgh, London, Melbourne, New York: Churchill Livingstone, 1982:242-266.
- Papanikolaou G, Tzilianos M, Christakis JI, Bogdanos D, Tsimirika K, Macfarlane J, et al. Hepcidin in iron overload disorders. Blood 2005;105: 4103-4105.
- Pietrangelo A. Hereditary hemochromatosis: a new look at an old disease. N Engl J Med 2004;350:2383-2397.
- Merryweather-Clarke AT, Cadet E, Bomford A, Capron D, Viprakasit V, Miller A, et al. Digenic inheritance of mutations in HAMP and HFE results in different types of haemochromatosis. Hum Mol Genet 2003;12: 2241-2247.
- Wallace DF, Clark RM, Harley HA, Subramaniam VN. Autosomal dominant iron overload due to a novel mutation of ferroportin1 associated with parenchymal iron loading and cirrhosis. J Hepatol 2004;40:710-713.
- Njajou OT, de Jong G, Berghuis B, Vaessen N, Snijders PJ, Goossens JP, et al. Dominant hemochromatosis due to N144H mutation of SLC11A3: clinical and biological characteristics. Blood Cells Mol Dis 2002;29:439-443.
- Pietrangelo A. The ferroportin disease. Blood Cells Mol Dis 2004;32:131
- Finch C. Regulators of iron balance in humans. Blood 1994;84:1697-1702.
- Nicolas G, Andrews NC, Kahn A, Vaulont S. Hepcidin, a candidate modiﬁer of the hemochromatosis phenotype in mice. Blood 2004;103:2841-2843.
- Weinstein DA, Roy CN, Fleming MD, Loda MF, Wolfsdorf JI, Andrews NC. Inappropriate expression of hepcidin is associated with iron refractory anemia: implications for the anemia of chronic disease. Blood 2002;100: 3776-3781.
- Drakesmith H, Schimanski LM, Ormerod E, Merryweather-Clarke AT, Viprakasit V, Edwards JP, et al. Resistance to hepcidin is conferred by hemochromatosis-associated mutations of ferroportin. Blood 2005 Apr 14; [Epub ahead of print].